Typically, in a small cabinet or card cage housing for PCB's, there is a frame containing a group of top and bottom guide channels within which individual circuit boards are slid into and out of the cage. Mounted on a rear edge of each board is at least one connector plug incorporating a number of pins which mate with corresponding holes in a connector socket in a connector module mounted at the rear end of each of said channels within the cabinet. Electrical connection between circuit board components, jumper wires, etc., is obtained by the mating of the plug with its associated connector socket.
Since many pin to hole connections must be made simultaneously with an insertion of a PCB, each engagement must be sufficiently resilient to allow for proper insertion even with pins that are slightly misaligned or bent or both. Consequently, the force necessary to insert or to remove a particular PCB can easily range from 9 to 26 lbs per connector. In the ensuing disclosure, the terms "insertion" or "injection" and "removal" or "ejection" of a PCB refer to a mounting operation which results in the connector plug and socket modules being mated to unmated. The terms do not denote additional unfettered sliding movements of the PCB's within the guide channels.
In many PCB installations, the front end of the board carries a face plate, which acts to close off the particular space in front of the frame location occupied by the PCB. Once all the boards are inserted, the face plates combine to present a substantially unbroken flat surface which acts to keep dust and other contamination away from the interior of the cabinet. However, with close packing of PCB's in the frame, when and if it is necessary to remove a particular PCB, there is often considerable difficulty in getting a good grip on the face plate in order to accomplish said withdrawal. This is particularly true for the initial ejection movement when the rear connector plug must be disengaged from its associated socket.
To assist in said injection and ejection, the front edge of the PCB may support one or more lever devices at the top and bottom edges thereof to generate the forces necessary for such movement. The prior art shows a number of such devices for performing this function such as those which are depicted in the following U.S. patents:
U.S. Pat. No. 4,313,150, dated July 26, 1982, to P. Chu; U.S. Pat. No. 4,233,646, dated Nov. 11, 1980, to E. C. Leung et al.; U.S. Pat. No. 4,197,572, dated Apr. 8, 1980, to M. Aimar; and U.S. Pat. No. 4,064,551, dated Sept. 20, 1977, to R. Lightfoot and attention is directed to them.
Many of these devices to generate the forces needed, are primarily designed to hook onto the front frame members of the cabinet and rotate around them. In so doing, the linear insertion forces also tend to develop small rotational moments at the front edge of the board. Such rotational moments cause the plug at the opposite end of the board to cock or tilt slightly which, if not causing the pins to bend, will tend to increase the magnitude of the linear forces needed to accomplish insertion and removal.
The present invention covers an apparatus for effectively injecting and ejecting a PCB from a rear connector socket so that said PCB can be readily inserted into and withdrawn from the frame without the deficiencies of the prior art as noted above. As disclosed herein the device provides for the generation of a direct linear force for such injection and ejection without generating undesirable rotational forces. It is therefore an advantage of the present invention that the forces generated to perform said injection and ejection are both linear and coplanar with the axis of the PCB with no rotational forces being developed at the pin/socket interface.